如何将新属性推入对象数组中的每个现有对象？

Question

I'm trying to retrieve a single result from a multi-dimensional array and then push that result into each object contained within an object array.

Here is my code;

 var data = { "questions": ["Q1", "Q2", "Q3"], "details": [{ "name": "Alex", "values": [27, 2, 14] }, { "name": "Bill", "values": [40, 94, 18] }, { "name": "Gary", "values": [64, 32, 45] }] } var question = "Q1"; var singleResult = []; for (var i = 0; i < data.details.length; i++) { var qIndex = data.questions.indexOf(question) singleResult.push(data.details[i].values[qIndex]) } for (var i = 0; i < singleResult.length; i++) { data.details.push({ single: singleResult[i] }) } console.log(data.details) 

As you can see it is pushing a new object into the array where as instead I would like the single result to be pushed into each of the existing 3 objects.

So my new array should look like;

[{
  "name": "Alex",
  "values": [27, 2, 14],
  "single": 27
}, {
  "name": "Bill",
  "values": [40, 94, 18],
  "single": 40

}, {
  "name": "Gary",
  "values": [64, 32, 45],
  "single": 64
}]

I thought running a loop with .concat would do the trick, but sadly it wasn't the case (for me at least!).

Hope everything is clear, thanks in advance for any help/advance!

Answer 1

I would refactor it like this:

 var data = { "questions": ["Q1", "Q2", "Q3"], "details": [{ "name": "Alex", "values": [27, 2, 14] }, { "name": "Bill", "values": [40, 94, 18] }, { "name": "Gary", "values": [64, 32, 45] }] } var question = "Q1"; var qIndex = data.questions.indexOf(question) data.details.forEach((obj) => { obj.single = obj.values[qIndex]; }); console.log(data.details) 

Highlights:

1. Getting your qIndex should be done outside of a loop - as it stays the same no matter what.
2. Using forEach loop instead of for loop is my personal preference for keeping code clean and readable - it would work exactly the same if you stick with for.
3. singleResult array seems unnecessary here as your goal was only to extend base objects in details with field single - so we completely removed it.

Answer 2

You can use indexOf() to get index of question and then map() to get modified array.

 var data = {"questions":["Q1","Q2","Q3"],"details":[{"name":"Alex","values":[27,2,14]},{"name":"Bill","values":[40,94,18]},{"name":"Gary","values":[64,32,45]}]} var question = "Q1"; var qIndex = data.questions.indexOf(question); var result = data.details.map(function(e) { var o = JSON.parse(JSON.stringify(e)); o.single = e.values[qIndex]; return o; }); console.log(result); 

Answer 3

 var data = { "questions": ["Q1", "Q2", "Q3"], "details": [{ "name": "Alex", "values": [27, 2, 14] }, { "name": "Bill", "values": [40, 94, 18] }, { "name": "Gary", "values": [64, 32, 45] }] } var question = "Q1"; var singleResult = []; for (var i = 0; i < data.details.length; i++) { var qIndex = data.questions.indexOf(question) singleResult.push(data.details[i].values[qIndex]) } for (var i = 0; i < singleResult.length; i++) { data.details[i].single = singleResult[i]; } console.log(data.details) 

Answer 4

 var data = {"questions": ["Q1", "Q2", "Q3"],"details": [{"name": "Alex","values": [27, 2, 14]}, {"name": "Bill","values": [40, 94, 18]}, {"name": "Gary","values": [64, 32, 45]}]}, question = "Q1", qIndex = data.questions.indexOf(question); for (var i = 0, len = data.details.length; i < len; i++) { data.details[i].single = data.details[i].values[qIndex]; } console.log(data.details);